310 THE LOP-NOR PROBLEM.
Grenard's views with regard to the Lop-nor are based upon the statements of Russian travellers, upon Richthofen's criticisms, and upon information which he himself received from the natives. But he seems to have had no sort of knowledge of the investigations which I made in 1896, and published the same year in Verhandlungen der Gesellschaft für Erdkunde zu Berlin and in Peternaanns Mitteilungen, at all events he makes no mention of them in his discussion, which appeared in the year 1898. The mistake into which he falls is easily explained, on the ground that he himself never visited the country of Lop, so that he draws the same erroneous inferences as, for instance, Delmar Morgan and Krapotkin have done. But in this historical sketch of the Lop-nor problem it would be an oversight not to allude to his contribution to the question. After explaining that the variability of the Lop-nor and neighbouring lakes is due to the inconstancy of the rivers, he proceeds: »Toutefois le Lob-nor même a été non pas déplacé, mais réduit par suite de la faiblesse des rivières qui l'alimentent, du limon qu'elles apportent et de l'évaporation très active à laquelle il est soumis. Le sol porte des traces d'une plus grande extension de la nappe aqueuse à une époque antérieure, et il est probable que le Kara Bourân s'étendait primitivement jusqu'à l'ancien confluent du Tarim et du Tchertchen-daria par 39° 54' de latitude. De même le Kara Kochoun devait s'étendre un peu plus au nord alors qu'il recevait le Kontche daria sur sa rive septentrionale. La carte des Ta Ts'ing nous montre sur la rive septentrionale du Kara Kochoun quatre petits lacs qui n'existent plus aujourd'hui; c'étaient évidemment des lacs formés par le Kontche daria, qui ont disparu lorsque cette rivière • a cessé de les alimenter. En se reportant à l'ouest, le Kontche daria en a formé quatre nouveaux qui ont remplacé les anciens et sont situés au nord-ouest de ceux-ci, le long du bras oriental actuel de la rivière. Ces lacs, dont j'ai eu connaissance par les indigènes, se nomment à partir du nord: Kara koul, Tayek koul, Sougout koul, Tokoum koul. ... Que ces lacs, qui n'en font qu'un seul en été . . . soient récents et causés uniquement par le Kontche daria, c'est ce dont on ne peut douter un moment.»
In analysing this passage I would call attention to the contradiction involved in first saying that the volumes of the rivers have not appreciably diminished during the last two thousand years, and then that the Lop-nor has, not indeed altered its position, but diminished, because of the feebleness of the rivers that feed it. To affirm that the Kara-buran formerly extended all the way to 39° 54' N. lat., that is to say as far as the ancient confluence of the Tarim and the Tschertschen-darja, is too bold an assumption to make; all the same it is fully excused through Roborovskij's hasty and misleading assertion, that the Tschertschen-darja formerly followed a much more northerly course through the desert. That the Kara-koschun has at times had a greater extension than it has now we know from direct observations made during the last 25 years, but the traces which those temporary extensions have left behind them, even at pretty considerable distances from the existing shores, have nothing to do with the desiccation of the basin of Central Asia, for this has been going on for countless ages; they depend rather upon oscillations in the volume, occasioned by the formation of marginal lakes and other factors mentioned above. On the other hand the Kontsche-darja has never terminated at the northern shore
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